Studies on gold nanoparticles supported on iron, cobalt, manganese, and cerium oxide catalytic materials

Gold nanoparticles containing iron, cobalt, manganese, and cerium materials were prepared using precipitation-deposition/co-precipitation methods. The techniques employed for the characterization of these materials were ICP-MS, TGA, TEM, XRD, BET, Mossbauer, and XAS. Au L-3-edge X-ray absorption spectroscopic measurements were carried out over a series of transition and rare earth materials containing gold nanoparticles. The size of gold nanoparticles varied in the range of similar to 3 to 7 nm in the Fe/Co/Mn/Ce materials. These materials possess medium between 34 and 63 m(2)/g. The XRD analysis of the samples indicated the high phase purity and crystallinity of the support (Fe/Co/Mn/Ce) materials. Mossbauer spectroscopy was employed to obtain valuable information on the electronic and crystallographic structure of gold nanoparticles. An X-ray absorption fine structure (XANES, EXAFS) technique was used in obtaining critical information about the atomic distances, bonding, and neighbouring environment for gold atoms in the Fe/Co/Mn/Ce materials. XAFS and in situ high temperature XRD techniques were used to investigate the influence of the high temperature treatment on gold nanoparticles inside the metal oxide materials. The results obtained from XAFS, XANES, XRD, and Mossbauer analysis confirm the typical characteristics and structure of gold nanoparticles in these materials.